*2.3. Motivation and Contribution of the Paper*

The number of articles, indicated in previous subsections, that concern simulation in recent years is huge. However, there is a lack of recent analyses realized for real cases although such real case analyses were common in the previous century. However, they are still necessary because the development of the materials and technics has totally changed in different areas. Thus, this article is a case study for the Russian power supply company "Oreolenergo" that concerns the analysis of restoration time in power lines based on analyzing historical data and a survey. In the analyzed regional power supply company "Oreolenergo", there are no monitoring systems for outages in the considered electrical networks. There is practically no automation equipment, and power lines are made radial. The structuring of the power supply restoration time given in the study makes it possible to consider in more detail all the constituents of the power supply restoration time and to establish the factors affecting it.

It is difficult to assess the real time of power supply restoration, since there is no real data on the time of the power supply outage beginning. The countdown of the power supply restoration time in most cases starts from the moment when the information on a failure is received by the dispatcher of a power supply company. As a result, restoration time is underestimated. Consequently, the damage from the undersupply of electricity is also inaccurate. Therefore, the constituent "time for obtaining information" was introduced into the structure of the power supply restoration time. The value of this constituent was determined by the Delphi method. This method was also used for the determination of the time for recognizing information. The choice of this method is due to the impossibility of evaluating the data on power supply restoration time constituents by other means. The questionnaires used for Delphi were designed specifically for this purpose and were sent to specialists who work in the power supply company "Oreolenergo" and who have at least five years of work experience. The choice of experts was justified by the fact that the dispatchers of the power supply companies receive information from consumers about power supply outages, register the moment of this information receipt, send a repair brigade to search for places of damage and to eliminate the identified damage, and register the corresponding time intervals for repairs and switching on. In most cases of power supply outages, especially in the 0.4 kV electrical network, dispatchers receive information about outages from consumers, since there are no monitoring systems for power supply outages. Nevertheless, they have cases of receiving information about the time of obtaining information, for example, during planned power supply interruptions made by the personnel of power supply companies. In these cases, they can register the time of disconnection and the moment of receipt of the information on the power supply outage from the consumer. Thus, there is the opportunity to analyze the time interval for obtaining information on power supply outages and the experts were competent in estimating time intervals for obtaining and recognizing information. A total of 20 experts

responded to the questionnaires. In turn, the repair time was determined by using the method of mathematical statistics, while the time for connection harmonization was determined by using the analysis of literature sources. To summarize the method's end elements indicated for the restoration time indication, Figure 1 was prepared. Additionally, in the article, the technical means of electrical network automation to reduce the power supply restoration time were also found.

**Figure 1.** The proposed methodology to obtain restoration time for a selected power supply company.
